[bumxumer]

Get an W8x48 I beam and incase it 60" below grade in concrete with about 3' of concrete above.

If he hits it after this upgrade, the driver will remember where that post is next time.

Oh and add like 100 of those little reflectors up and down your road along with a 8'x10' sign that reads "chad's mailbox is here" with a blinking arrow pointing towards the mailbox.

Of course we don't have snowplows around here, but rural mailboxes get plowed nonetheless by drunks. I've seen some fine examples out in the country of "Ok, try this one on for size" which would total an automobile if hit.